An integrated circuit (IC) device includes a fin-type active region extending on a substrate in a first lateral direction. A gate line extends on the fin-type active region in a second lateral direction. The second lateral direction intersects the first lateral direction. A channel region is between the substrate and the gate line. A source/drain region is adjacent to the gate line on the fin-type active region and has a sidewall facing the channel region. A superlattice barrier is between the substrate and the channel region. The superlattice barrier is in contact with the source/drain region. The superlattice barrier has a structure in which a plurality of first sub-layers including a semiconductor layer doped with oxygen atoms and a plurality of second sub-layers including an undoped semiconductor layer are alternately stacked.